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Date: Mon, 22 Mar 2010 14:35:00 -0000
Message-ID: <6dc9ffc81003220735k54fbef51o4f5c9ebec06fffa7@mail.gmail.com>
Subject: Re: [RFA 3/5] Prec: x86 segment register support: target
From: "H.J. Lu" <hjl.tools@gmail.com>
To: Hui Zhu <teawater@gmail.com>
Cc: Michael Snyder <msnyder@vmware.com>, Daniel Jacobowitz <dan@codesourcery.com>,  	gdb-patches ml <gdb-patches@sourceware.org>
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On Mon, Mar 22, 2010 at 7:02 AM, Hui Zhu <teawater@gmail.com> wrote:
> Thanks Michael and Daniel.
>
> I make a patch to add base of segments registers to x86-32:
> (gdb) info reg
> eax =A0 =A0 =A0 =A0 =A0 =A00xffffd514 =A0 =A0 =A0 -10988
> ecx =A0 =A0 =A0 =A0 =A0 =A00x1eda96c5 =A0 =A0 =A0 517641925
> edx =A0 =A0 =A0 =A0 =A0 =A00x1 =A0 =A0 =A01
> ebx =A0 =A0 =A0 =A0 =A0 =A00xf7fb1ff4 =A0 =A0 =A0 -134537228
> esp =A0 =A0 =A0 =A0 =A0 =A00xffffd488 =A0 =A0 =A0 0xffffd488
> ebp =A0 =A0 =A0 =A0 =A0 =A00xffffd488 =A0 =A0 =A0 0xffffd488
> esi =A0 =A0 =A0 =A0 =A0 =A00x8048510 =A0 =A0 =A0 =A0134513936
> edi =A0 =A0 =A0 =A0 =A0 =A00x80483d0 =A0 =A0 =A0 =A0134513616
> eip =A0 =A0 =A0 =A0 =A0 =A00x8048487 =A0 =A0 =A0 =A00x8048487 <main+3>
> eflags =A0 =A0 =A0 =A0 0x246 =A0 =A0[ PF ZF IF ]
> cs =A0 =A0 =A0 =A0 =A0 =A0 0x23 =A0 =A0 35
> ss =A0 =A0 =A0 =A0 =A0 =A0 0x2b =A0 =A0 43
> ds =A0 =A0 =A0 =A0 =A0 =A0 0x2b =A0 =A0 43
> es =A0 =A0 =A0 =A0 =A0 =A0 0x2b =A0 =A0 43
> fs =A0 =A0 =A0 =A0 =A0 =A0 0x0 =A0 =A0 =A00
> gs =A0 =A0 =A0 =A0 =A0 =A0 0x63 =A0 =A0 99
> cs_base =A0 =A0 =A0 =A00x0 =A0 =A0 =A00
> ss_base =A0 =A0 =A0 =A00x0 =A0 =A0 =A00
> ds_base =A0 =A0 =A0 =A00x0 =A0 =A0 =A00
> es_base =A0 =A0 =A0 =A00x0 =A0 =A0 =A00
> fs_base =A0 =A0 =A0 =A00x0 =A0 =A0 =A00
> gs_base =A0 =A0 =A0 =A00xf7e528d0 =A0 =A0 =A0 -135976752
>
> I try it in x86-32 pc and 32bit code in x86-64. =A0It works OK.
>
> Please help me review it.
>
> Best regards,
> Hui
>
> 2010-03-22 =A0Hui Zhu =A0<teawater@gmail.com>
>
> =A0 =A0 =A0 =A0* features/i386/32bit-linux.xml (org.gnu.gdb.i386.linux): =
Add
> =A0 =A0 =A0 =A0cs_base, ss_base, ds_base, es_base, fs_base and gs_base.
> =A0 =A0 =A0 =A0* i386-tdep.h (i386_segment_base_regnum): New enum.
> =A0 =A0 =A0 =A0* amd64-linux-nat.c (GDT_ENTRY_TLS_MIN,
> =A0 =A0 =A0 =A0GDT_ENTRY_TLS_MAX): New marco.
> =A0 =A0 =A0 =A0(ps_get_thread_area): New extern.
> =A0 =A0 =A0 =A0(amd64_linux_fetch_inferior_registers): Add
> =A0 =A0 =A0 =A0code to get 32 bits segment registers base.
> =A0 =A0 =A0 =A0* i386-linux-nat.c (GDT_ENTRY_TLS_ENTRIES,
> =A0 =A0 =A0 =A0GDT_ENTRY_TLS_MIN,
> =A0 =A0 =A0 =A0GDT_ENTRY_TLS_MAX): New marco.
> =A0 =A0 =A0 =A0(ps_get_thread_area): New extern.
> =A0 =A0 =A0 =A0(i386_linux_fetch_inferior_registers): Add
> =A0 =A0 =A0 =A0code to get segment registers base.

Are we going to support them on other OSes? If not,
the contents of i386_segment_base_regnum should be
moved to i386-linux-tdep.h and those values should
be after

/* Register number for the "orig_eax" pseudo-register.  If this
   pseudo-register contains a value >=3D 0 it is interpreted as the
   system call number that the kernel is supposed to restart.  */
#define I386_LINUX_ORIG_EAX_REGNUM I386_SSE_NUM_REGS

In any cases, they shouldn't be hard-coded to any values.
Otherwise, it won't work with AVX, which will add more registers.


--=20
H.J.